WO97/45908 discloses a wind power park where each wind turbine is equipped with a synchronous generator. The output power of the synchronous generator is rectified by means of an AC/DC rectifier and transmitted through a DC transmission cable to a DC/AC inverter and a transformer so as to be transferred to the regional supply network. The AC/DC rectifier comprises controlled rectifiers, which are able to compensate for possible variations in the speed of rotation through a suitable control by means of particular control circuits. However, such control circuits are rather complicated.
WO 92/14298 and WO 99/007996 disclose a variable speed wind turbine comprising active power converters for providing AC power. These power converters include active controlled rectifiers and require expensive controller circuits.